Shav, also known as Sorrel Soup can be either served hot or cold, but I prefer it as a cold soup. After it is chilled in the refrigerator, I add into each individual bowls a chopped up hard boiled egg and a dab of sour cream. Sorrel leaves are expensive, so I use spinach instead and you can hardly taste a big difference (provided sour salt is used). This soup can be found in Jewish cuisines and known in Russian, Polish and other eastern European countries. Served this tasty soup with an old style hard crusted pumpernickel bread and enjoy!